1. Field of the Invention
Embodiments relate to a hardmask composition and associated methods. More particularly, embodiments relate to a hardmask composition for processing a resist underlayer film, a method of forming the hardmask composition, and a method of producing a device using the hardmask composition.
2. Description of the Related Art
An antireflective coating (ARC) material may be used to minimize reflectivity between a resist material layer and a substrate, in order to attain better resolution in a lithographic process. However, similarities in the composition of the ARC and the resist material layer may result in poor etch selectivity between the ARC material and the patterned resist layer. Accordingly, portions of the resist layer may be undesirably consumed during etching of the ARC after patterning.
Resist materials used in some lithographic techniques do not provide resistance to the subsequent etching step to an extent sufficient to effectively transfer a desired pattern to a layer underlying the resist material. For example, a resist pattern may be used as a mask to etch a substrate, e.g., a silicon oxide film, but miniaturization of circuits has resulted in a reduction of the thickness of resists, making it difficult for the resists to act as masks. As a result, etching of oxide films without any damage is difficult. Accordingly, a hardmask has been used to etch an underlying resist underlayer film, e.g., where an extremely thin resist material is used, a substrate to be etched is thick, a large etching depth is needed, and/or the use of a particular etchant is required. The hardmask plays a role as an intermediate layer between a patterned resist and a substrate to be patterned, and serves to transfer a pattern of the patterned resist to the substrate. Therefore, the hardmask should be able to withstand etching used to pattern the substrate.
A resist pattern may be transferred to an underlayer film for processing an oxide film, followed by dry etching the oxide film using the pattern-transferred underlayer film as a mask. The underlayer film for processing the oxide film may be a film that is formed under an antireflective film to function as an underlayer antireflective film. In this process, since the etch rate of the resist may be similar to that of the underlayer film, it may be necessary to form a mask between the resist and the underlayer film to etch the underlayer film. Specifically, an underlayer film for processing an oxide film, a mask for processing the underlayer film (i.e., a hardmask for processing the resist underlayer film) and a resist may be sequentially formed on an oxide film. Such a multilayer structure is shown in FIG. 1.
It is generally known that a structurally stable hardmask having a high silicon content exhibits improved etch resistance to an oxygen-based etching gas. A siloxane, e.g., a product of polycondensation of alkylsilyl and silyl hydride compounds, may be used to form a hardmask having an increased silicon content. However, typical silyl hydride compounds are sufficiently reactive to undergo uncontrollable condensation reactions, even in the presence of a small amount of water without the use of an additional catalyst. In addition, the highly reactive silane compounds tend to be gelled during condensation or purification. These disadvantages make it difficult to synthesize a polymer having required physical properties using such silane compounds. Also, due to poor stability of the polymer, it may be difficult to prepare a solution of the polymer that is stable during storage.